## Midterm Information

### CSG140 Computer Graphics - Spring 2004 - Prof. Futrelle

### Updated 21 February

The Midterm Exam will be in class on Thursday, March 18th.

It will be a closed book, closed notes exam.
Note that the Final Exam, which will include some more advanced material,
will be open book, open notes.

There are two types of information intermixed here:
The sections of the textbook you are responsible for as well
as the types of questions you'll be responsible for in each
section. Needless to say, the exam cannot cover every topic
below. It will focus on approximately four of the eight topics below.

**Planes:** (Chap. 2) Section 2.7.1 and 2.7.2. Be able to manipulate and compute
from representations f(x,y,z) = ax + by + cz = 0,
(**p** - **a**)⋅**n** = 0 and the related cross products
that give the normal.
**Triangles:** (Chap. 2)
Be able to answer a question involving equations 2.29 through 2.31.
**Line drawing:** (Chap. 3) I would give you the algorithm on pg. 58 and ask you
to iterate it numerically for a few steps and explain why it's often
more efficient than simply evaluating y = mx + b at each point.
**2D transformations:** (Chapter 5) You must be able to correctly write out
and compute with 2D rotations and translations. You should get the order
of multiplication straight and know that inverses can be simply decomposed
so that if M = ABC, then
M^{-1} = C^{-1}B^{-1}A^{-1}.
**Shading:** (Chap. 8) You should understand and memorize
equation 8.2, and able to draw figure 8.1 and explain its relation to the equation.
For the Phong lighting model,
I may give you Fig. 8.5 and ask you to explain equation 8.5 qualitatively,
using an eyepoint close to the reflected ray and one not as close. For this
you need to understand the cosine function and how a high power of it behaves
close to θ = 0. You should also be able to explain
what Phong normal interpolation is used for - what artifact it avoids and
how it avoids it.
**Ray tracing:** (Chap. 9) In Sec. 9.3.1, you should be able to
derive the equation that precedes the A, B, C form on page 155, starting
with the simple equations for a ray and a sphere at the top of the page.
Explain the significance of the double, single and imaginary roots for *t* in the
resulting equation.
**Shadows:** (Chap. 9). Be able to explain, along with carefully drawn
diagrams corresponding to sections 9.5 and 9.11.2, how shadows and soft
shadows are computed.
**Texture mapping:** (Chap. 10) [details to be added after 2/26 class]

Go to CSG140 home page.
or RPF's Teaching Gateway or
homepage